Pressure control system



July 7, 1959 R. w. ERICKSON PRESSURE CONTROL SYSTEM Filed March 24,' 1958 gabs@ BEQ u v N K N VEN TOI?.- Roberf u. Erickson A 7 TORNEYS.

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Illlrllllllk United States Patent PRESSURE CONTROL SYSTEM Robert W. Erickson, Chicago, Ill., assignor to Universal Uil Products Company, Chicago, Ill., a corporation of Delaware Application March 24, 1958, Serial No. 723,570

` 4 claims. (c1. zs--zs The present invention relates to a pressure control system and is specifically directed to the control of individual operating pressure levels within a single, integrated process, or within a combination process comprising two or more individual processes. The pressure control system of the present invention is particularly advantageous when applied to those combination processes in which it is either desired or necessary to conduct a gaseous material from a low-pressure zone into a highpressure zone, both of which zones are integrated within the single combined process.

Virtually all of the processes employed within commercial industries require the utilization of pressure as a determinable variant for the purpose of the overall control of the multitude of reactions eected therein. The control of operating pressure is by no means, however, restricted to those processes wherein various reactions, or combinations of reactions, are effected. Many processes, in which it is desired specifically to inhibit reactions of any kind, are commonly practiced, and the ecient control of the operating pressure aords a convenient method for insuring substantial non-reactivity within such processes.

Processes employed for the treating of various raw materials, and/or the treating of the products of various reactions, for the purpose of electing the removal of contaminants and substances which tend to exert detrimental effects toward the desired result, are generally considered to come Within the second-named category, that of processes in which non-reactivity is of prime importance. Those processes which are utilized for the specific purpose of effecting certain reactions, or combinations of reactions, are numerous and are found extensively throughout the petroleum, heavy chemical, detergent, pharmaceutical industries, etc. Similarly, numerous reactions are effected therein and include dehydrogenation, aromatization, dehydrocyclization, hydrogenation, sulfonation, isomerization, alkylation, combinations thereof, etc.

As hereinbefore stated, many processes exist as distinct combinations; that is, two or more of the above mentioned reactions are simultaneously effected, each of which has a designedly different function in attaining the desired combined result. For example, the dehydrogenation of naphthenes into the corresponding aromatic hydrocarbons is often preceded by a suitable treating process wherein the naphthene-containing hydrocarbon charge to the dehydrogenation reaction zone is first subjected to hydrogenation for the purpose or insuring complete saturation of the oleiinic-type hydrocarbons. The treating process also serves the function of removing various metallic and non-metallic contaminants which, if allowed to remain within the hydrocarbon charge, tend to exert deleterious effects upon the catalytic composite employed in the subsequent dehydrogenation zone, and tend to inhibit rather than promote' the desired, reactions. Other combined processes, frequently encountered, encompass such combinations as the reforming of hydrocarbons,

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followed by subsequent isomerization of the low-mo-y lecular weight parafns; reforming of hydrocarbons, followed by the subsequent alkylation of the resulting aromatic hydrocarbons, etc. It is understood that these com- An object of the present invention is to control these various operating pressure levels through the use of anovel pressure control system. A specific object of -thepresent invention is to effect the control of such pressure levels in those processes which necessarily require the transportation of a gaseous material from a portion ofthe combination process which operates at a relatively low pressure level, toat least one portion of the combined process which operates at a significantly higher pressure level.

In one embodiment, the present invention provides a pressure control system which comprises in combination a first pressure-tensing means sensing the pressure in a low-pressure reaction zone and operating a rst pressure-controlling means within a high-pressure reaction zone, a second pressure-sensing means sensing the pressure in said high-pressure reaction zone and operating a second pressure-controlling means within said lowpressure reaction zone, wherein at least a portion of the gaseous reaction products from said low-pressurev zone are passed through said second pressure-controlling means into said high-pressure reaction zone, and at least a portion of the gaseous reaction products are removed from said high-pressure zone through said first pressure-controlling means.

In a specific embodiment, the present invention providesv a pressure control system for use in a process consisting of a high-pressure hydrogenation zone and a lowpressure dehydrogenation zone, in which combined process said hydrogenation zone is maintained at a pressure at least about l0 pounds per square inch greater than the pressure maintained within said dehydrogenation zone,

and wherein at least a portion of the gaseous reaction products from said dehydrogenation zone are caused to pass into said hydrogenation zone and at least a portion of the gaseous reaction products from said hydrogenation reaction zone are returned to said hydrogenation zone,

" which pressure control system comprises in combination a iirst pressure-sensing means sensing the pressure in said dehydrogenation zone and operating a iirst pressure-controlling means within said hydrogenation zone, and a second pressure-sensing means sensing the pressure within said hydrogenation zone, operating Va second pressurecontrolling ymeans within said dehydrogenation zone and a third pressure-controlling means within said hydrogena-` p tions hereinafter set forth. As hereinbefore stated, the hydrogenation system serves a multitude of functions, of which the complete satura-` tion of olefmic hydrocarbons is of major importance, from lthe standpoint of avoiding deleterious elects when' vthe hydrogenated reaction products are subsequently sub-' Patented July 7, 1959 However, it yis understood that the pressure control jected to the reforming zone. To achieve the desired result, it is necessary that large quantities of hydrogen be supplied,to, and are, present within, the -hydrogenatitmY gaseous reaction product from the reforming zone, sinceat least two of the primary reactions effected therein are the dehydrogenation o f naphthenes into aromatic hydrocarbons` and lrthe dehydrocyclization of straight-chain and branched-chain parafins into aromatic hydrocarbons,

General1y, the hydrogenation or treating zone willl opcrate at la 4relatively high pressure, within the range of about 500 to 800 pounds per square inch, for the purpose of substantially completely suppressing undesirable side reactions, while simultaneously promoting the saturation of the oletlnic hydrocarbons. On the other hand, the reforming reaction zone or dehydrogenation zone will have imposed thereon a pressure which is consistent with, and beneficial for the promotion of, the desired end result. That is, higher pressures, within the range of about- 60G-to 1000 pounds per square inch, are generally employed when operating to effect the most optimum balance between the multitude of reactions effected within the reforming process, and lower pressures, within the range of from about 300 to about 600 pounds per square inch, when operating for the primary purpose Vof* singularly promoting only one or -two specific reactions. In those instances -Where the dehydrogenation reaction zone is maintained underan imposed pressure greater than that pressure under which the hydrogenation zone is maintained, there exists no particularv problem in attaining efficient control of the'pressure levels while simultaneously transporting the hydrogen-rich gaesous product from the dehydrogenation zone to the hydrogenation zone.

Where, however, the dehydrogenation zone is designedly operated under an imposed pressure which is less than that imposed upon the hydrogenation zone, an obvious diiiiculty arises in supplying the hydrogen to the hydrogenation zone, and continuing to effect eliicient pressure controly of the entire system. The pressure control system of' the instant invention eliminates this diliiculty without introducing substantialadditional equipment into theprocess, such as an additional compressor and the necessary attendant manifolding, additional controls, valves, etc., while permitting individual recycle of gaseous material-through each of the separate zones. The utility of the present invention is readily ascertained through reference to the accompanying drawing hereinafter described in detail. Miscellaneous controls, valves, heaters, coolers, process piping, and other similar appurtenances have either been limited therein or entirely omitted therefrom. These are obvious and self-evident,

and do not particularly lend to a clear understanding ofv the method of the present invention. ItA is understood that the present invention is not limited to the particular process hereinafter set for-th, or limited unduly in excess of the spirit and intended scope of the appended claims.

With reference to the drawing, liquid and gaseous reaction products from reaction zone 1, in the high pressure system, are passed through line Z into separation zone 3; A separation is effected 4therein whereby normally gaseous material passes-into line 4 containing pressure control valve S; the liquefied product from separation zone 3 is removed through line 6. Compressor 7 obtaines suction from line 4, and discharges a predetermined quantity o f the gaseous products from separation zone 3 through'line 8 into reaction zone 1.

VLiquid and gaseous reaction products from, reaction zone 9, in the .1o-w pressure-System, are passedthrough. line 1.!) into separatemv zone, 1.1. The;Y ligueed prod-- 4 the normally gaseousv material is removed via. line 13. A predetermined quantity ofthe normally gaseous material is drawn through line 13 by compressor 14 and is recycled 'through line 15 into reaction zone 9. The excess gaseous material from scparation zone 11 passes through line 16 containing control valve 17, and is com- Y mingled with the gaseous. rnaterialin line 4 at a point uct from separation zone 11 is removed via line 12', and 75 upstream of pressureY control: valve 5 and' downstream of compressor 7- In some situations, it will be desired not to cause any of the gaseous reaction products from separation zone 3 to be incorporated linto the gas stream being recycled through compressor 7 and line 8 into reaction zone 1. When these situations arise, that'portionof line 4 which contains control valve 5 is eliminated. However, when employed, control valve 5 may operate as a back-pressure control valve: as illustrated, 0r it may be actuated by pressure-sensing. means 19, which actuation is not illustrated. The actuation of both control valve 17 and control valve, 5 by pressure-sensing means 19, is one of the specific embodiments ofthe present invention.

The operating pressure in reaction zone 1 is sensed, via line 18, by pressure recorder-controller 19. Pressure recorder-controller 19 actuates pressure control valve 17 in the low pressure system, causing excess gaseous material to ow through line 16and may actuate control vale 5 in line 4 (when not eliminated as hereinabove set forth), causing gaseous reaction products from zone 3 to be recycled to reaction zone 1. The operating pressure in reaction zone 9 is sensed through line 20 by 'pressure recorder-controller 2.1iy which actuates pressure control valve 22 in line 2,3, causing excess gaseous material to be removed from the high-pressure system.

To illustrate further the method of the present invention, whereby accurate, eliicient pressure control is obtained in a system which comprises, as an integral function therein, the transmission of large quantities of gaseous material from a low pressure zone into a high pressure zone, it will be assumed that the pressure in reaction` zone 1 commences to increase above the desired, predetermined level which is recorded and controlled by pressure recorder-controller 19. This high pressure is sensed via line '18 by recorder-controller 19 and causes pressure control valve 17 to close. The closing of pressure coutrol valve 17 effects an increase in the operating pressure in reaction zone 9, the latter being sensed via line 20 by recorder-controller 21. Recorder-controller 21 actuates pressure control valve 22 causing this valve to open, thereby venting excess gaseous material from the high pressuresystem, whereby the pressure therein is lowered. As the pressure in reaction zone 1 falls below the level controlled by recorder-controller 19, the latter actuates.

control valve 17 whereby this valve opens, and the excess pressure upon reaction zone 9 is released through line 16.

As hereinabove set forth, pressure control valve 5` is required in those instances in which at least a portion of the-gas which is recycled through reaction zone 1, is withdrawn from separation zone 3. In those instances, where it is desired that none of the gaseous material from separation zone 3 should pass into reaction zone 1, pressure control valve l5, and thatportion of line 4, containing the same may be eliminated from the system. When control valve 5 is an integral part of the system, and is being,V actuated by pressure,recorder-controller 19, it will be sety bination a first pressure-sensing means sensing the pressure in a low-pressure zone and operating a first pressure-y controlling means within` a high-pressure reaction 29.118,

a second pressure-sensinsmcans. .sensing` the4 prcssurain,

saidihgh-pmsure zone and. operating a .Second pressure: controlling means within said low-pressure zone whereby at least a portion of the gaseous reaction products from said low-pressure zone are passed through said second pressure-controlling means into said high-pressure zone, and at least a portion of the gaseous reaction products are removed from said high-pressure zone through said first pressure-controlling means.

2. The pressure control system of claim l further characterized in that the pressure maintained within said highpressure zone is at least about ten pounds per square inch greater than the pressure maintained within said lowpressure zone.

3. The pressure control system of claim 1 further characterized in that at least a portion of the gaseous reaction products from high-pressure zone is passed through a third pressure-controlling means operated by said second pressure-sensing means, and is recycled therethrough into said high-pressure zone.

4. A pressure control system for use in a process consisting of a high-pressure hydrogenation zone and a lowpressure dehydrogenation zone, in which process said hydrogenation zone is maintained at a pressure at least about ten pounds per square inch greater than the pressure maintained within saiddehydrogenation zone, and wherein at least a portion of the gaseous reaction products from said hydrogenation reaction zone are returned to said hydrogenation zone, which pressure control system comprises in combination -a trst pressure-sensing means sensing the pressure in said dehydrogenation zone and operating a. first pressure-controlling means within said hydrogenation zone, and a second pressure-sensing means sens` ing the pressure within said hydrogenation zone operating a second pressure-controlling means within said dehydrogenation zone causing at least a portion of the gaseous reaction products from said dehydrogenation zone to pass into said hydrogenaton zone, and a third pressurecontrolling means within said hydrogenation zone.

References Cited in the iile of this patent UNITED STATES PATENTS Murphy Feb. 16, 1943 

1. A PRESSURE CONTROL SYSTEM WHICH COMPRISES IN COMBINATION A FIRST PRESSURE-SENSING MEANS SENSING THE PRESSURE IN A LOW-PRESSURE ZONE AND OPERATING A FIRST PRESSURECONTROLLING MEANS WITHIN A HIGH-PRESSURE REACTION ZONE, A SECOND PRESSURE-SENSING MEANS SENSING THE PRESSURE IN SAID HIGH-PRESSURE ZONE AND OPERATING A SECOND PRESSURECONTROLLING MEANS WITHIN SAID LOW-PRESSURE ZONE WHEREBY AT LEAST A PORTION OF THE GASEOUS REACTION PRODUCTS FROM SAID LOW-PRESSURE ZONE ARE PASSED THROUGH SAID SECOND PRESSURE CONTROLLING MEANS INTO SAID HIGH-PRESSURE ZONE AND AT LEAST A PORTION OF THE GASEOUS REACTION PRODUCTS 